> - we should reserve an input or two for "manufacturing" jumpers
> so that s/w can run some internal diagnostics and board test stuff
I was planning to see what was left of the I/O pins on the 3730 for
just the reason. Maybe if we run out, we need a spare PAL to implement
these plus some LEDs.
> - save a few bits to read the SIMM ID bits, so that s/w can know
> what size DRAM is installed in each bank and 'do the right thing'
You don't need that. Its possible to figure it out in S/W.
> - a name for the %^*%(* thing, how about 'Foghorn' (after Foghorn
> Leghorn of course) If that is too Americentric, feel free to suggest
> something else. Waldorf Salad? LOAM (Linux on a MIPS)?
Good plan, but don't quit your day job.
> - for serial/parallel ports on board, how about a 16C552 - two
> 16550 uarts and a IBM compatible centronics parallel port with 8 bit
> cpu interface. Made by TI and others. Also don't forget those
> pesky line interface chips.
I still think that parallel should go on the ISA bus. I know its cheap,
but this thing is getting too expensive. As for RS-232 drivers,
Motorola 145406, has 3 transmitters and 3 receivers. You need one
per port.
> - does someone have a heat chamber to test this thing at elevated
> temperature for a while? It may be GPL h/w, but it doesn't have to
> be flaky...
My kitchen at about 3pm gets to about 110F!! :-) (The sun gets
it just the wrong way.)
> - think about cooling options for the CPU. The 33MHz 79R3051E in the MJ
> package runs pretty hot - I'm sure the 40MHz 3081E will really cook,
> especially with more cache on chip. I would plan on a heat sink and/or fan.
> Don't burn your hands :-)
My NCD-19r (with has a LSI r3k) runs warm at 33MHz; cooler than my 486.
There are temperature specs in the 3081 data sheets. We just need to
check it, as you say.
> - for debug, put some headers around the CPU for each pin. If you only
> run the local bus to the 3730 it will be hard to hook a logic analyzer to
> either the 3730 or the 3081 without using expensive test clips.
The logic analysers that I have access to come with those clips. In any
case, Waldorf want a socket next to the CPU, so this would do.
> - we should budget for appropriate filters and such for EMI. If waldorf
> wants to sell this commercially it will have to pass VDE and/or FCC
> (or CISPR) and/or other agency approvals. Does Waldorf have a
> site where they can scan the unit? Or are they going to do their own
> layout and only test their version?
Hell, I forgot about FCC. Isn't that a requirement before any sales in
the US? I've only done designs for the Australian market which doesn't
need FCC (or anything). Has someone gone though this before?
--
Neil Russell (The wizard from OZ)
Pyramid Technology Email: caret@pyramid.com
3860 N. First Street Voice: (408) 428-7302
San Jose, CA 95134-1702 FAX: (408) 428-8845